package com.wjf.wjfaiagent.chatmemory;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;
import org.objenesis.strategy.StdInstantiatorStrategy;
import org.springframework.ai.chat.memory.ChatMemory;
import org.springframework.ai.chat.messages.Message;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;

public class FileBasedChatMemory implements ChatMemory {

    private final String BASE_DIR;
    private static final Kryo kryo = new Kryo();

    static {
        kryo.setRegistrationRequired(false);
        // 设置实例化策略
        kryo.setInstantiatorStrategy(new StdInstantiatorStrategy());
    }

    public FileBasedChatMemory(String dir){
        this.BASE_DIR = dir;
        File baseDir = new File(this.BASE_DIR);
        if (!baseDir.exists())
            baseDir.mkdirs();
    }
    @Override
    public void add(String conversationId, List<Message> messages) {
        List<Message> messageList = getOrCreateConversation(conversationId);
        messageList.addAll(messages);
        saveConversation(conversationId, messageList);
    }

    @Override
    public List<Message> get(String conversationId, int lastN) {
        List<Message> messages = getOrCreateConversation(conversationId);
        return messages.stream().skip(Math.max(0, messages.size() - lastN)).toList();
    }

    @Override
    public void clear(String conversationId) {
        File file = getConversationFile(conversationId);
        if (file.exists())
            file.delete();
    }


    private void saveConversation(String conversationId, List<Message> messages){
        File file = getConversationFile(conversationId);
        try (Output output = new Output(new FileOutputStream(file))){
            kryo.writeObject(output, messages);
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 获取或创建指定会话id的消息列表
     * @param conversationId
     * @return
     */
    private List<Message> getOrCreateConversation(String conversationId){
        File file = getConversationFile(conversationId);
        List<Message> messages = new ArrayList<>();
        if (file.exists()){
            try (Input input = new Input(new FileInputStream(file))){
                messages = kryo.readObject(input, ArrayList.class);
            } catch (FileNotFoundException e) {
                throw new RuntimeException(e);
            }
        }
        return messages;
    }
    // 获取会话 id 对应会话文件对象
    private File getConversationFile(String conversationId){
        return new File(BASE_DIR, conversationId + ".kryo");
    }

}
